/*
** $Id: lparser.h,v 1.76 2015/12/30 18:16:13 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#ifndef lparser_h
#define lparser_h

#include "llimits.h"
#include "lobject.h"
#include "lzio.h"


/*
** Expression and variable descriptor.
** Code generation for variables and expressions can be delayed to allow
** optimizations; An 'expdesc' structure describes a potentially-delayed
** variable/expression. It has a description of its "main" value plus a
** list of conditional jumps that can also produce its value (generated
** by short-circuit operators 'and'/'or').
*/

/* kinds of variables/expressions */
typedef enum {
    VVOID,  /* when 'expdesc' describes the last expression a list,
             this kind means an empty list (so, no expression) */
    VNIL,  /* constant nil */
    VTRUE,  /* constant true */
    VFALSE,  /* constant false */
    VK,  /* constant in 'k'; info = index of constant in 'k' */
    VKFLT,  /* floating constant; nval = numerical float value */
    VKINT,  /* integer constant; nval = numerical integer value */
    VNONRELOC,  /* expression has its value in a fixed register;
                 info = result register */
    VLOCAL,  /* local variable; info = local register */
    VUPVAL,  /* upvalue variable; info = index of upvalue in 'upvalues' */
    VINDEXED,  /* indexed variable;
                ind.vt = whether 't' is register or upvalue;
                ind.t = table register or upvalue;
                ind.idx = key's R/K index */
    VJMP,  /* expression is a test/comparison;
            info = pc of corresponding jump instruction */
    VRELOCABLE,  /* expression can put result in any register;
                  info = instruction pc */
    VCALL,  /* expression is a function call; info = instruction pc */
    VVARARG  /* vararg expression; info = instruction pc */
} expkind;


#define vkisvar(k)  (VLOCAL <= (k) && (k) <= VINDEXED)
#define vkisinreg(k)    ((k) == VNONRELOC || (k) == VLOCAL)

typedef struct expdesc {
    expkind k;
    union {
        lua_Integer ival;    /* for VKINT */
        lua_Number nval;  /* for VKFLT */
        int info;  /* for generic use */
        struct {  /* for indexed variables (VINDEXED) */
            short idx;  /* index (R/K) */
            lu_byte t;  /* table (register or upvalue) */
            lu_byte vt;  /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
        } ind;
    } u;
    int t;  /* patch list of 'exit when true' */
    int f;  /* patch list of 'exit when false' */
} expdesc;


/* description of active local variable */
typedef struct Vardesc {
    short idx;  /* variable index in stack */
} Vardesc;


/* description of pending goto statements and label statements */
typedef struct Labeldesc {
    TString* name;  /* label identifier */
    int pc;  /* position in code */
    int line;  /* line where it appeared */
    lu_byte nactvar;  /* local level where it appears in current block */
} Labeldesc;


/* list of labels or gotos */
typedef struct Labellist {
    Labeldesc* arr;  /* array */
    int n;  /* number of entries in use */
    int size;  /* array size */
} Labellist;


/* dynamic structures used by the parser */
typedef struct Dyndata {
    struct {  /* list of active local variables */
        Vardesc* arr;
        int n;
        int size;
    } actvar;
    Labellist gt;  /* list of pending gotos */
    Labellist label;   /* list of active labels */
} Dyndata;


/* control of blocks */
struct BlockCnt;  /* defined in lparser.c */


/* state needed to generate code for a given function */
typedef struct FuncState {
    Proto* f;  /* current function header */
    struct FuncState* prev;  /* enclosing function */
    struct LexState* ls;  /* lexical state */
    struct BlockCnt* bl;  /* chain of current blocks */
    int pc;  /* next position to code (equivalent to 'ncode') */
    int lasttarget;   /* 'label' of last 'jump label' */
    int jpc;  /* list of pending jumps to 'pc' */
    int nk;  /* number of elements in 'k' */
    int np;  /* number of elements in 'p' */
    int firstlocal;  /* index of first local var (in Dyndata array) */
    short nlocvars;  /* number of elements in 'f->locvars' */
    lu_byte nactvar;  /* number of active local variables */
    lu_byte nups;  /* number of upvalues */
    lu_byte freereg;  /* first free register */
} FuncState;


LUAI_FUNC LClosure* luaY_parser( lua_State* L, ZIO* z, Mbuffer* buff,
                                 Dyndata* dyd, const char* name, int firstchar );


#endif
